Dave left the stage to applause. Then the spotlights flickered into life and the 200 or so fans, sweating and smiling in the attic of the Camden Assembly began to make their way very quickly to the exit. The headline show, which was his first, had been a success. Not because it had sold out in a day, or that he had been joined on stage by his friend AJ Tracey, or that he had paced himself this time round, not running out of breath as he had done at an appearance in the summer. But because, as he stood on the small elevated stage, doused in a pink hoodie and a sharp skin fade, and peered down into the room, he noticed that many of the strangers scattered in the crowd were overcome with emotion, and in that moment he knew that the songs and freestyles he had written in the bedroom of his Mum's house in Streatham, South London, spoke to people in a dimension beyond just music.

"I will always call you guys my supporters and my friends," he told them. "And just like you support me, I will always support you."

Since Giggs and friends first blew the doors off UK rap, there have been many acts touted to spearhead its renaissance. At the tender age of 18, it is now Dave who has been earmarked to push the genre to new levels. But, in a way, he's already been doing it for some time. In only a few adolescent years, Dave has released his Six Paths EP, and carved out a style of rap that hones in on the existential angst of a generation growing up in a world with more opportunity and uncertainty than ever. Sometimes he makes melodic rap with auto-tuned hooks fit for any house party, at other times he's crafting 16's for grime cuts that dominate sweaty raves and radio sets. His freestyles have touched souls and his sing-along rap bangers are impossible to shake.

Importantly, the world has noticed: just two months ago, Drake took Dave's "Wanna Know", repackaged it with two Champagne Papi verses, and then broke the internet by dropping it on his OVO radio show. And yet, Dave is composed: he sees himself as neither a rapper, nor an MC, nor a singer. To him, he's just Dave, who makes music, music that people enjoy and now pay to see him perform live.

Backstage after the show, the Streatham artist is still smiling to himself, satisfied with how the gig has gone, looking forward to doing again at his national tour in a few months. He towels himself off and then slips through a side door into the fresh winter evening. On the busy Camden side street, he's spotted by around fifty supporters who swarm him like bees around honey, anxious and impatient, pushing up close against him, thrusting their iPhones into his face, and clicking away for their personal Instagram's and Twitter's and SnapChat's. The co-sign from Drake didn't just mean a spike in Spotify streams and Twitter followers; it meant big fame real fast, and for the first time in the evening Dave seems overwhelmed. "Oh my God," he mumbles to himself, jostling for space, "this is mad."

A few days later, the adrenaline of the show having fizzled and faded, he sits quietly in the very neat front room of his manager's central London apartment. He's in a dark-blue windbreaker and a set of lean taper-fit jeans. The pockets are empty. His iPhone is shattered, in disrepair, and on it's way to the Apple Shop. His ID and bank cards are both missing, gone with his recently lost wallet. He's got no passport now too, and has zero cash in his pockets. He's frustrated, for he's a man with many things to do and no means with which to do them. He could no longer hear the ring of the Camden Assembly in his ears, or feel the hot breath of the rushing crowd on his face, and for a moment he seemed to miss it.

"It felt strange, it felt crazy," he says, rocking gently on a computer chair, "to have people respect what I'm doing, to take a likeness, to care enough to speak to me afterwards and take pictures. It felt kind of surreal."

This frenzied momentum of support has been gathering for almost 18 months now. He caught his very first wave of attention back in 2015, when he released a freestyle on UK rap YouTube channel Bl@ckbox. Sixteen-years-old and broke at the time, he skated train to train across London to the Bl@ckbox studio in Essex where the small crew were ready and waiting to record. While many in his age group were channelling road rap through the bouncy one-line flows and pounding Chiraq instrumentals that would eventually become the UK drill scene, Dave went deeper, sharing close-to-heart stories of rampaging inner turmoils.

For four minutes he barked over the sinister instrumental about visiting his older brothers in prison, the ache of watching his mother struggling to deal with a family breaking apart and the setbacks and stumbling blocks he was facing growing up around violence and social ills in inner city London. "Every boy's a trapper till the shit hits the fan, and then the shit hits the wall, you're flushing bits of the raw," he raps in the opening lines, "And every girl's a trap queen till they kick in the door, and now you're in the station telling stories like Roald Dahl". It was vivid social commentary, conscious but not preachy, observational but firmly rooted in his own reality.

"That just comes from growing up in Streatham," he explains. "If you don't have that observational streak, anything could happen. It's something you need to have because there's so much to lose and so much to gain. Where I'm from, if you can't see who and what is good for you and who is bad for you, you could end up with the wrong friends, in places where you don't need to be, with people that you didn't need to bring into your house, giving your trust to those who could turn on you."

Dave's Bl@ckbox freestyle began to blow up online, just as he was finishing up in school and moving onto college. He had always been something of an outlier, and tells me he couldn't focus at school, but when at home, in his free time, he would lose himself in film scores by Steve Jablonsky and Hans Zimmer. He even flunked the required reading for his GCSE's but learnt to play piano at a Grade 7 by spending hours poring over tutorials on YouTube. In his downtime he partnered his love for UK rap with an interest in anime, and when not doing either of those, he spent his hours drawing. "I guess," he says with a shrug, "I just go out and do my own thing."

Once settled in at college – where he studied philosophy, ethics, law and music – he got back to music, balancing his A-Levels with the release of his first official music videos. The first, "JKYL + HYD" was filmed on a set of concrete steps not far from his home, and would revisit his inner conflicts. Despite being blessed with an intuitive wisdom, he still found himself tempted by the quick money and street life he often warned others against in his music. It was a theme that would consistently crop up in his raps. During his 'Fire In The Booth' in March 2016, he described himself as a cross between Heath Ledger and Malcolm X because "one day it's put the knives down or put the peace signs up, the next day I'm at your home instead".

"I was just trying to find balance," he explains, "between telling people the right things to do and at the same time upholding those same standards that I give for everyone else."

Still figuring it all out, he continued down his own path, balancing melody with message, building a reputation for vivid, visceral storytelling and a perspective on life beyond his years. The next few months moved quickly. Co-signs came in from most of the urban scenes heavy hitters, as did the care packages from the fashion brands. In "Thiago Silva" with AJ Tracey, he flexed his versatility by releasing one of the grime anthems of 2016, and then flew out to Paris to shoot the video. For "Wanna Know" he took his boys to Venice. In the spring and summer he flooded the festival circuit, but still found time to climb into the studio to finish recording the Six Paths EP. It was a labour of love – crafted by Dave himself, his long term producer Tyrell '169', and Fraser T Smith. They resisted the temptation to sample and instead weaved together six tracks of original music. Dave played the keys, Fraser handled the guitar and Tyrell laid the basslines.

What emerged was a project that seamed together his fractured tastes in music, and proved that he could consistently channel the same emotion and energy from his freestyles into structured three minute songs. It earned him a spot on the BBC Music Sound of 2017 longlist and before long he had been crowned as the urban scene's heir apparent, the next one up; but UK rap's prince in waiting did not feel like the prince. "I don't see myself as part of any scene really,'' he said. "I'm not trying to be confined to a genre. I'm not a grime act, I'm not a rapper, nor am I melody man. I just make music."

For now it seems, he's content with just being himself. "One moment this is working so everyone is doing that," he says. "Then something else is working so everyone is doing that. Everyone is what is now but no one is what is them or what is forever."

The past year had been a string of short-lived highs and humbling bumps back to Earth. He had pushed rental Benz's around sunny LA, only to find himself topping up his Oyster Card in Streatham the next day. He had graced the stage at the Royal Opera House but had also taken time out to visit his brothers in prison. He had travelled the world over and met fans in far flung continents, but today he had no passport, no wallet, no recognised proof of his existence. He now made songs with GRAMMY winning producers but still insisted on flooding his music video's with his pals from South London.

And what was often forgotten, among all of these peaks and valleys, was that he was still an 18 year old kid. He was still fond of anime (though he no longer had the time to watch); he worked through the nights and slept in the afternoons, he was loyal to Manchester United, and when he smiled, he revealed a mouth that glistened with four silver teeth. He seemed to always be on the edge of two worlds, of ecstasy and mind-numbing routine, of the surreal and of Streatham.

"The two extremes are so crazy," he said. "But I guess I do appreciate the lifestyle that I live now. The biggest lesson that I've learnt is that things can change so quickly, never get used to one thing because everything can flip on it's head. Just be thankful for what you have in the moment, but most importantly, work hard. The things that you work hard on have a lot of impact."

Evening began to toll again. The sun dipped under the horizon, leaving the apartment in shadowy dusk. He had plans to meet a friend later, if he could get hold of a phone. Beyond that, in his bigger picture, he saw awards and world domination. He was prepared to play the long game, he said. Success had come quickly to Dave but he's a patient guy. He's now well accustomed to the unpredictability of life, and he's holding tight onto the approach that he's always had: to just keep being himself.